Potent, selective inhibitor of VEGFR-2 tyrosine kinase (IC50 = 0.9 nM). Displays some inhibitory activity towards c-Kit, PDGFRα and FGFR-2 (IC50 values range from 40 to 170 nM) but is highly selective over other receptor tyrosine kinases (IC50 > 10000 nM for FGFR-2, EGFR and HGFR). Inhibits VEGF-stimulated proliferation of human umbilical vein endothelial cells (HUVEC) and inhibits tumor growth in vivo; antiangiogenic.